Definitions
OWASP describes source code analysis tools, also known as Static Application Security Testing tools, as tools that analyse source code or compiled code to help find security flaws.
OWASP describes web application vulnerability scanners, the category known as Dynamic Application Security Testing, as automated tools that scan web applications, normally from the outside, to look for vulnerabilities such as cross-site scripting, SQL injection, command injection, path traversal and insecure server configuration.
The differences side by side
| Aspect | SAST | DAST |
|---|---|---|
| What it examines | Source code or compiled code, at rest. | A deployed, running application, over HTTP. |
| Needs the source | Yes. | No. It sees what an outside visitor sees. |
| When it can run | From the first commit, in the editor or in CI. | Once there is something running, such as a staging site. |
| Points to the line of code | Yes. OWASP lists file, line number and code snippet output as a strength. | No. It reports a URL, a parameter and a response. |
| Finds configuration problems | OWASP lists this as a weakness: configuration is often not represented in the code. | Can find what is visible from outside, such as missing headers or insecure server configuration. |
| Known weak spots | OWASP says many authentication problems, access control issues and insecure cryptography use are difficult to find automatically, and that false positives are high. | Sees only what it can reach. Pages behind login, multi-step flows and business rules need setup or manual testing. |
| Language dependence | Tied to the languages and frameworks the tool supports. | Independent of language, since it speaks HTTP. |
What SAST leaves to you
- Triage. Someone has to decide which findings are real. OWASP notes it is often hard to prove a flagged issue is an actual vulnerability.
- Access control review. A static tool does not know that user A must not read user B's invoice.
- Configuration outside the code, such as database rules in a hosted dashboard, storage bucket settings and environment variables.
- Dependencies, unless your tool also does dependency scanning, which is a separate technique.
What DAST leaves to you
- Coverage. A scanner tests the pages and endpoints it discovers. Give it authenticated access to staging if you want it to see past the login page.
- Finding the cause. You get a URL and a payload, and you still have to locate the code.
- Business logic, such as changing a price in the request or skipping a payment step.
- Permission. Only scan systems you own or have written approval to test.
How they fit a small team
NIST's Secure Software Development Framework treats code review or analysis and testing of executable code as separate practices, and asks organisations to decide where each applies. For a small team that usually means a static check and secret scan on every commit, a dynamic scan against staging before releases, and a manual two-account test of access rules.
For apps built with AI tools, much of the risk sits in hosted configuration such as database policies. Neither SAST nor DAST reads that reliably, so check it directly.
What to check whichever you pick
- Findings are triaged and tracked, not left in a report nobody reads.
- Secret scanning runs on the repository and its history.
- Dependency scanning runs on every change to the lockfile.
- Access control is tested by hand with two accounts and a logged-out visitor.
- Hosted configuration, such as database rules and storage buckets, is reviewed separately.
- Scans run against staging with test data, and only on systems you are authorised to test.
Frequently asked questions
What is the difference between SAST and DAST?
SAST reads your code without running it and can point to the exact line. DAST attacks the running app from outside and shows what a visitor could exploit. They find different problems.
Do I need both SAST and DAST?
They complement each other. If you can only start with one, pick based on your biggest gap: static checks and secret scanning are cheap to add to every commit, while a dynamic scan shows what is exposed on your live or staging site.
Can SAST find broken access control?
Often not. OWASP lists access control issues among the problems that are difficult for static tools to find automatically. Test access control by hand with two accounts.
Is a dependency scanner the same as SAST?
No. Dependency scanning, often called software composition analysis, checks third-party packages against known vulnerabilities. SAST analyses the code you wrote. Many products bundle both.